Mo-9Si-8B-3Hf alloy consisting of a Mo solid solution and intermetallic phases Mo(3)Si and Mo(5)SiB(2) was fabricated by hot pressing sintering to yield a fine microstructure with all three phases being in the size range of micrometer. The tensile properties of this alloy were evaluated in vacuum at elevated temperatures. This alloy displayed extensive plasticity or superplasticity at temperatures ranging from 1400 degrees C to 1560 degrees C with strain rate of 3 x 10(-4) s(-1). The tensile elongation of 410% was measured at 1560 C. Grain boundary sliding was the main mechanism of plastic deformation for this alloy. (c) 2011 Elsevier B.V. All rights reserved.